Course 1 Unit 1

Lesson 4 Investigation 2-Plots Over Time

Page 80


Consider the plot over time graph reproduced from page 80 and answer the questions in your text.

1. From the plot of life expectancy, you can see how the life expectancy of each group has changed over time, how the groups compare at any one time, and how the changes for the groups compare.

a. What is the expectancy of black females born in 1920?

b. Which group had the greatest increase between 1940 and 1950?

  • How can you see this from the plot?

c. What happened to the life expectancy of males born between 1960 and 1970?

d. Where is the only place in the plot that two lines cross?

  • Describe what is happening there.

e. According to the plot, what is your life expectancy: ______

f. Describe the trends in the plot. From the evidence in the plot, how high do you think life expectancies will be for people born in the year 2010?

2 Use the table on the bottom of page 81.

a. What does a rating of 4.07 for the 1998 Mustang indicate about the repair records for that Mustang?

b. Which 1994 car had the fewest problems?

  1. Use the plot shown on page 82

a. Use the plot to estimate the average repair rating for the model year 1996 Ford Mustang.

b. Between which model years was there the greatest change in the ratings?

  • How does the plot help you see that change?

c. Describe the change in the ratings for the Mustang over the 7-year span.

d. If you were considering buying a Mustang, how could you use this information to help make your decision?

4. Your teacher will show you how to make a plot over time using your TI-83 graphing calculator. Produce a plot over time of the Mustang repair ratings for the model years from 1994 to 2000.

a. How does the plot on your calculator compare to the one in Activity 3? Trace along the plot and check the coordinate readouts against the data table.

b. Change Ymin to 0 and Ymax to 5.

  • Does the new plot change your perception (visual impression) of the amount of

change in the ratings?

  • What happens if you set the x-axis to begin at 0 and end at 105, with a scale of 5?
  • Use the automatic scaling option for statistical plots, if your graphing tool has one. How did this alter your plot?

c. Compare the average repair ratings for the Mustang and the Intrepid by graphing them on the same plot over time.

d. Change Ymin to 0 and Ymax to 10, with Yscl = 1. How does this change your perception of the two sets of ratings?

e. What would happen to the plots and your perception of the change in ratings over the years if you changed the minimum value of x to 60 and the maximum value of x to 105?

  • Do you think this is a reasonable way to represent the data? Why or why not?

Checkpoint:

In this investigation, you explored how to interpret and make a plot over time.

  1. Describe a plot over time.
  1. What information can you learn from a plot over time?
  1. How can you use a plot over time to find the time period when the least change occurs?
  • The most?
  1. How can the scales on the axes affect your interpretation of a plot over time?

Course 1 Unit 1 Lesson 4 Investigation 2Page 1 of 5